package com.zsy.springframework.beans.xml;

import cn.hutool.core.util.StrUtil;
import cn.hutool.core.util.XmlUtil;
import com.zsy.springframework.beans.facotry.config.BeanDefinition;
import com.zsy.springframework.beans.facotry.config.BeanReference;
import com.zsy.springframework.beans.facotry.config.PropertyValue;
import com.zsy.springframework.beans.facotry.exception.BeansException;
import com.zsy.springframework.beans.facotry.jiekou.one.BeanDefinitionRegistry;
import com.zsy.springframework.beans.facotry.support.AbstractBeanDefinitionReader;
import com.zsy.springframework.resourceloader.jiekou.Resource;
import com.zsy.springframework.resourceloader.jiekou.ResourceLoader;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;

import java.io.IOException;
import java.io.InputStream;

//resourceloader加载进来之后是xml文件的话，需要走这个解析的
//将xml标签对应到beandefinition当中
//上面有个接口 BeanDefinitionReader 可以根据情况进行加载选择
//不一定都是xml的文件
public class XmlBeanDefinitionReader extends AbstractBeanDefinitionReader {

    //因为父类写了两个非空参数的构造，所以默认的空参构造不生效，
    // 所以子类继承后，无法调用父类的默认构造

    public XmlBeanDefinitionReader(BeanDefinitionRegistry registry, ResourceLoader loader) {
        super(registry, loader);
    }

    public XmlBeanDefinitionReader(BeanDefinitionRegistry registry) {
        super(registry);
    }

    //下面的方法都是通过这个方法来操作的，无非就是多遍历几次操作
    //这种操作在源码中很常见，提高代码的复用
    @Override
    public void loadBeanDefinitions(Resource resource) throws BeansException {
        try (InputStream inputStream = resource.getInputStream()) {
            doLoadBeanDefinition(inputStream);
        } catch (IOException | ClassNotFoundException e) {
            throw new BeansException("IOException parsing XML document from " + resource, e);
        }
    }

    @Override
    public void loadBeanDefinitions(Resource... resources) throws BeansException {
        for (Resource resource : resources) {
            loadBeanDefinitions(resource);
        }
    }

    @Override
    public void loadBeanDefinitions(String path) throws BeansException {
        ResourceLoader loader = getResourceLoader();
        Resource resource = loader.getResource(path);
        loadBeanDefinitions(resource);
    }

    @Override
    public void loadBeanDefinitions(String... paths) throws BeansException {
        for (String path : paths) {
            loadBeanDefinitions(path);
        }
    }

    //具体就是从xml文件中读取资源
    private void doLoadBeanDefinition(InputStream inputStream) throws ClassNotFoundException {
        Document doc = XmlUtil.readXML(inputStream);
        Element root = doc.getDocumentElement();
        NodeList childNodes = root.getChildNodes();

        for (int i = 0; i < childNodes.getLength(); i++) {
            // 判断元素
            if (!(childNodes.item(i) instanceof Element)) continue;
            // 判断对象
            if (!"bean".equals(childNodes.item(i).getNodeName())) continue;

            // 解析标签
            Element bean = (Element) childNodes.item(i);
            String id = bean.getAttribute("id");
            String name = bean.getAttribute("name");
            String className = bean.getAttribute("class");
            // 获取 Class，方便获取类中的名称
            Class<?> clazz = Class.forName(className);
            // 优先级 id > name
            String beanName = StrUtil.isNotEmpty(id) ? id : name;
            if (StrUtil.isEmpty(beanName)) {
                beanName = StrUtil.lowerFirst(clazz.getSimpleName());
            }

            // 定义Bean
            BeanDefinition beanDefinition = new BeanDefinition(clazz);
            // 读取属性并填充
            for (int j = 0; j < bean.getChildNodes().getLength(); j++) {
                if (!(bean.getChildNodes().item(j) instanceof Element)) continue;
                if (!"property".equals(bean.getChildNodes().item(j).getNodeName())) continue;
                // 解析标签：property
                Element property = (Element) bean.getChildNodes().item(j);
                String attrName = property.getAttribute("name");
                String attrValue = property.getAttribute("value");
                String attrRef = property.getAttribute("ref");
                // 获取属性值：引入对象、值对象
                //判断这个bean是否有人用过了
                Object value = StrUtil.isNotEmpty(attrRef) ? new BeanReference(attrRef) : attrValue;
                // 创建属性信息
                PropertyValue propertyValue = new PropertyValue(attrName, value);
                beanDefinition.getPropertyValues().addPropertyValue(propertyValue);
            }
            if (getRegistry().containsBeanDefinition(beanName)) {
                throw new BeansException("Duplicate beanName[" + beanName + "] is not allowed");
            }
            // 注册 BeanDefinition
            getRegistry().registerBeanDefinition(beanName, beanDefinition);
        }
    }
}
